For filling up the system you will use 9 liters of special Red coolant type. In other way 1987 B-Series won’t be used quite long and efficiently. It’s important to provide cooling for Mazda’s engine with 2.0 liters volume. It’s better to choose fluid in combination of 2003 year, 2.5 volume of motor and engine code of WLE7. For Mazda B-Series it’s important to have optimal antifreeze inside.
It’s obvious that every R290 motor needs good service as stated by Mazda in instruction. Providing you keep the rules 2.2 motor installed in B-Series of 1987 year will be long lasting. If you choose other than Red coolant or use less than 7 liters, you can’t expect normal work. It will be advantageous to follow Mazda’s rules for 1990 B-Series service.